Can arbuscular mycorrhizal fungi and biochar enhance plant resistance to low-temperature stress?

Improving plant resistance to abiotic stress, such as low temperature, is conducive to plant normal growth and development. The aim of this study was to clarify whether arbuscular mycorrhizal fungi (AMF) and biochar have a synergistic effect on plant growth and resistance to low-temperature stress in perennial ryegrass (Lolium perenne L.). A pot experiment was conducted to measure the effects of AMF (Glomus intraradices) inoculation, biochar addition (4%, w/w), and their combination on the biomass, inorganic ion contents, antioxidant enzyme activities, and osmotic regulator contents in L. perenne plants growing under room temperature and low temperature conditions. A saline soil with the total salt content of 5.21 g kg(-1) was used in the experiment. Results showed that the AMF-only treatment decreased biomass growth under room temperature condition, whereas the biochar-only treatment increased total biomass under low temperature condition. The combined treatment with AMF and biochar evidently increased biomass growth via a synergistic effect under both room temperature and low temperature conditions. Under low-temperature stress, the AMF- and biochar-only treatments increased proline content in the plant leaves. Meanwhile, superoxide dismutase and peroxidase activities were enhanced substantially in the AMF-only group compared to the control group. The combined treatment with AMF and biochar considerably increased catalase activity and proline content and reduced malondialdehyde content in the plant leaves under low-temperature stress. In conclusion, AMF and biochar exhibited a synergistic effect in promoting plant growth of L. perenne and played a role in improving plant resistance to low-temperature stress in the saline soil.